Nounverb
hint - A small or subtle piece of advice, suggestion, or information, often given to help someone understand something or solve a problem.

After a difficult 30 minutes in front of the group, my manager gave me a hint on how to improve my presentation.
ambush - To suddenly attack someone after hiding and waiting for them:
The brigade walked quietly to the hidden spot on the hill, patiently until the enemy walked in the valley below, so that they could ambush the unsuspecting enemy, who were taken by surprise.